The present invention relates to a boat for loading semiconductor wafers. More particularly, the present invention relate to a wafer boat for a vertical furnace, which is used in a semiconductor manufacturing process.
Semiconductor chips must undergo numerous processes for integrated circuits (ICs) to be formed on them. Some of these processes are thermal treatment processes involving the use of a boat loaded with wafers that is inserted into a furnace. The furnaces used in these processes can be categorized as horizontal or vertical furnaces depending upon the orientation of the wafer boat. A horizontal furnace has the wafer boat introduced horizontally into the furnace, while a vertical furnace has the wafer boat introduced vertically.
FIGS. 1 and 2 are a perspective view and a sectional view, respectively, of a conventional wafer boat 11 for use in a vertical furnace. The boat is made of quartz and has a plurality of slots 13 formed on its inside. These slots 13 are evenly spaced between the lower and upper plates 31 and 33, which are installed on either end of the wafer boat 11. The slots 13 are evenly spaced to make them most efficient for loading wafers. Holes 35 are formed on the lower plate 31. These holes 35 allow the wafer boat 11 to be fixed to the furnace by pins (not shown) inserted into the holes 35 when the wafer boat 11 is inserted into the furnace. Inside each slot 13, an upper corner 25 is provided with a sloped surface, while a lower corner 27 has a right angle.
According to the above conventional wafer boat 11, particles off of the wafer boat 11 tend to collect on the lower corners of the slots 13, forming a protrusion that can cause damage to the loaded wafers. This damage in turn can cause a deterioration of the reliability of semiconductor devices formed on the wafers. In addition, after the wafer boat 11 has been locked into the furnace several times, the holes 35 can become worn and enlarged, thus reducing the useful life of the wafer boat 11.